How plastic wends its way to ocean garbage patches

Plastic bags float in the sea. Researchers have identified the currents and winds that cause plastic particles to accumulate at sites in the Arctic and elsewhere. Credit: Getty

Environmental sciences

01 March 2019

Wind and wave action drive the build-up of microplastics at remote ocean sites.

Small pieces of floating plastic pose an increasing threat to marine species, but human-made microplastic particles are not distributed evenly throughout the seas.

Victor Onink at Utrecht University in the Netherlands and his colleagues used a model of ocean currents to investigate which physical processes control the accumulation of plastic particles in ‘garbage patches’ of the ocean. They found that wind-driven circulation of the upper ocean is responsible for the high concentration of plastic debris in certain regions of the subtropical North Pacific and North Atlantic oceans.

By contrast, the team found that wave movement, another component of large-scale ocean circulation, seems to increase the amount of microplastic reaching the remote Arctic Ocean. Because some particle-transport models still don’t account for wave-induced drift, plastic pollution in the Arctic might be worse than commonly estimated, the scientists say.